This invention relates to a coal plow cutter with a cutter foot that forms a cutter shank and a cutter head that comprises at least one coal face cutting edge, whereby the coal face cutting edge has at least one pin as a cutting body that is made of highly wear-resistant material and is anchored in a recess in the cutter head.
The closest prior art is the plow cutter described in DE 295 037 43 U1 with a floor blade and a coal face cutting blade, in which the floor blade is formed from a cutting insert that is made of highly wear-resistance material such as hard carbide in particular, and the coal face cutting blade is formed from highly wear-resistant pins that are inserted in borings. In the coal plow cutter of the prior art, as a result of the presence of the pins on the coal face cutting blade, during operation of the plow the solder seams of the cutting insert, which has a large surface area, are subjected to lower stresses on the floor cutting blade, as a result of which the useful life of the coal plow cutter is improved. The purpose of soldering the pins is to prevent the erosion of the support material, and the purpose of the inserted pins is to prevent damage to the cutting edges even when the plow is moving in reverse.
The object of the invention is to improve the useful life of coal plow cutters of the prior art using economical measures, even under the increasing loads that result from higher rates of face advance or greater cutting depths.
The invention teaches that the pin has a conical pin head, whereby the external surface of the cone-shaped pin head has a curved dome shape, and/or the cutter has a floor blade that comprises at least one pin that is made of highly wear-resistant material. The conical pins with a curved, dome-shaped external surface that are provided in accordance with one aspect of the invention not only have a better cutting action than the pins with rounded pin heads that are used in the prior art, but they also result in fewer blowouts on the solid cutting insert made of hard carbide that may optionally be present on the front side.
In the preferred configuration, both the pins located on the floor blade as well as the pins located on the coal face blade have a conical pin head with a curved, dome-shaped external surface. The pins can be glued, clamped or preferably soldered into the recesses that preferably consist of blind holes in the plow head.
In the particularly preferred configuration, on the upper side of the cutter head farther from the cutter foot there is at least one pin that has a conical pin head with a conical dome-shaped external surface. This pin head that is located on the upper side results in an increased cutting capacity of the cutter and simultaneously protects the surface of the plow head and additional cutting heads or cutting inserts when the plow is moving in reverse. During the reverse movement, the plow is moved along the working face in the direction opposite to the cutting direction for the respective coal plow cutter. The pin on the upper side of the cutter head can in particular form a component of the floor blade, and can project with its pin tips beyond the upper edge of a frontal cutting body of the floor blade, so that during operation of the plow, the stresses on the frontal cutting bodies in the main cutting zone are reduced. The frontal cutting body can be a cutting insert, for example, whereby the cutting insert can have larger dimensions than configurations of the prior art because the forces that are exerted on the cutting insert are lower. The tip of the pin head of the pin that is associated with the floor blade projects on the upper side beyond the upper edge of the cutting insert preferably by a minimum of 1 mm and a maximum of approximately 2 mm. In an alternative configuration, the frontal cutting body can also consist of an additional pin, the pin head of which then preferably has a larger diameter than the pin heads of the other pins that are made of highly wear-resistant material.
In the particularly preferred configuration, the pin heads of the pins on the upper side of the cutter head are oriented diagonally relative to the direction of movement or cutting of the plow, whereby the external surface of the respective pin head that points in the cutting direction of the pins on the upper side is inclined more steeply with respect to the cutting direction than the external surface on its rear side. On account of the inclined position of the pins, a greater cutting capacity is achieved, and simultaneously a more favorable application and introduction of the working forces into the cutter head and the anchoring of the pins. On account of the greater forces that can absorbed with the inclined position of the pins on the upper side, the forces that are introduced into a frontal cutting insert are also further reduced.
In one configuration of a coal plow cutter that preferably forms a bottom blade, the upper side of the cutter head can be bordered by two essentially flat arms that run toward each other at an angle on an apex line, whereby the pin or pins on the upper side is/are located on the apex line. On a symmetrical cutter, the apex line hereby runs in the center, and on an asymmetrical cutter it runs eccentrically. Also advantageously, in one configuration, the cutting insert that forms the frontal cutting bodies can be realized in a triangular shape, whereby the arms on both sides of the cutting insert and/or behind the cutting insert in the cutting direction are provided with pins that are realized as taught by the invention to reduce the loads exerted on the cutting insert. The borings in the cutter head into which these pins are inserted are preferably inclined by 45° relative to the center plane of the cutter foot. The cutting insert can in particular be soldered with wire mesh into a countersunk edge in the cutter foot. The pins are preferably made of hard carbide and the cutter bodies with the cutter head and cutter shank are realized in one piece from a forging.